Pretty much the central feature of Facebook. Like the name says, it notifies the user of any activity his or her friends do on the site, from new photo albums to wall posts to status updates and comments to them. It debuted on September 1, 2006 and created a considerable controversy due to privacy concerns. Later on updates included a mini-feed on one's profile that shows all stories pertaining to just that person.

all my friends on facebook found out about my photo album when it was posted since it showed up on the news feed